In a long term evolution (LTE) system, a base station senses a quality status of a downlink channel through a channel quality indication (CQI) that is fed back by a user equipment, so as to help to perform frequency selective scheduling. In a long term evolution-advanced (LTE-A) system, a carrier aggregation technology is selected to support a wider bandwidth to satisfy a requirement of the International Telecommunication Union for a peak data rate of the 4th generation communication technology. Meanwhile, a coordinated multiple point transmission and reception (CoMP) technology is selected to improve coverage of the system for high-data rate users and increase a throughput at a cell edge and a system throughput. The CQI is a type of channel state information (CSI). In the carrier aggregation technology, one user equipment may access multiple downlink component carriers concurrently. In the CoMP technology, one user equipment may access multiple cells concurrently. When the user equipment accesses multiple downlink component carriers and/or cells concurrently, how to schedule and feed back CSI on a data channel becomes a problem that needs to be further researched.
In the LTE system and the LTE-A system, CSI feedback scheduled through a scheduling grant command on a data channel is also referred to as aperiodic CSI feedback. Currently, a method for transmitting the aperiodic CSI feedback includes: concurrently sending or receiving aperiodic CSI feedback information of all cells or downlink component carriers which a user equipment accesses, or increasing a length of an aperiodic CSI feedback request field in an uplink scheduling grant command; allocating an aperiodic CSI request field to each cell or each downlink component carrier; and sending or receiving aperiodic CSI feedback information of all or a part of cells or downlink component carriers to be fed back.
When the number of cells and/or carriers of the user equipment is larger, the number of bits for concurrently sending or receiving aperiodic CSI is large, which easily causes a waste of uplink resources. In addition, transmission performance of an aperiodic CSI can be guaranteed only with a good channel condition. Increasing the length of the CSI request field reduces reliability of the scheduling grant command. Meanwhile, it also causes a difficulty in the design of the grant so as to support multiple types of lengths of the CSI request field.